Integrated drive-generator (IDG) systems and starter-drive-generator (SDG) systems are well known as can be seen, by way of example, in U.S. Pat. Nos. 3,576,143; 3,786,696; 4,046,029; 4,252,035; and 4,315,442. In all such conventional systems, it is common to supply lubricating fluid to various sections such as the generator, the gear case and the full case hydraulic section by filling the various system component sections without recognition of the fact that various sections have different oil needs. Thus, by filling one section to sufficient capacity, it is possible that other sections will be overfilled when servicing because of the different oil lubrication and cooling schemes.
The management of fluid allocation and servicing levels becomes even more difficult because of the demand for lighter weight and more efficient aircraft engine accessories. For example, with state-of-the-art IDG systems, typically there are provided right and left pumps and motors, each with variable and fixed displacement hydraulic units, with which are associated a planetary differential and a conduction-cooled generator. These systems can encounter catastrophic failure as a result of overfilling during servicing, high heat rejection and inconsistencies in the filling procedure which result from misallocation and servicing levels of the fluid. No consideration has been given in such systems to the desirability of distinct fluid management for the major components of these systems.